The delivery of a drug to a patient with controlled-release of the active ingredient has been an active area of research for decades and has been fueled by the many recent developments in polymer science. In addition, controlled release polymer systems can be designed to provide a drug level in the optimum range over a longer period of time than other drug delivery methods, thus increasing the efficacy of the drug and minimizing problems with patient compliance.
Biodegradable particles have been developed as sustained release vehicles used in the administration of small molecule drugs, proteins, peptide drugs, and nucleic acids. The drugs are typically encapsulated in a polymer matrix which is biodegradable and biocompatible. As the polymer is degraded and/or as the drug diffuses out of the polymer, the drug is released into the body.
Currently, many methods exist for forming nanoparticles of biodegradable polymers. However, due to the slow partitioning of hydrophilic molecules into the hydrophobic nanoparticle core, methods of encapsulating charged hydrophilic agents, such as nucleic acids, have been plagued by low encapsulation yield, low drug-to-carrier weight ratios, irreproducibility, and often require emulsification at high shear rates to achieve nanoparticle size, resulting in product losses.
Thus, there is a need for a method of incorporating hydrophilic therapeutic agents into nanoparticles.